1. Field of the Invention
The invention pertains to a guide for an endless chain having multiple chain links on a track-type undercarriage for cranes.
2. Description of the Related Art
A guide of the general type in question is known from U.S. Pat. No. 4,229,053. The track-type undercarriage includes an undercarriage support, a drive sprocket wheel provided with chain teeth, an idler, an endless chain with multiple chain links, several track rollers, and a guide for the endless chain. Each link of the chain has two guide webs, which are symmetric to the center, spaced a certain distance apart, and aligned in the travel direction. The webs have engaging surfaces which ride on opposed circumferential flanges on the sprocket wheel. A cog connects the two webs below the engaging surfaces and meshes with the teeth of the drive sprocket wheel. The guide has a U-shaped carrier extending across the lower run, to the bottom of which individual elongated rails are detachably connected by bolts; the rails are held in mounting blocks. When the guide function is in effect, the inside surfaces of the rails come in contact with the outside surfaces of the guide webs.
This known design is very complicated in terms of design and represents a good deal of dead weight. In addition, the design makes it difficult to install or remove the track rollers.
The object of the invention is to provide a guide for the multi-link endless chain of a track-type undercarriage, which is compact in design and weighs less. Another object is to provide a guide which does not interfere with the installation and removal of the track rollers.
According to the invention, the guide, which is located immediately in front of or behind the drive sprocket wheel, is designed as a compact pivoting part, which is attached to a frame part of the undercarriage support. Two elongated webs serve as rails which, when the pivoting part is in its working position, are at least level with the upper area of the guide webs of the individual chain links.
This arrangement offers the advantage that the guide can be small and can be easily installed in the intermediate space between the last track roller and the drive sprocket wheel, whereas the rubber spring element provided in a recess prevents the pivoting part from rattling on the endless chain. The pivoting capacity offers the advantage that, when a chain link bends upward, the pivoting part can give way to allow this movement. Special attention has been paid to the ability to recognize the condition of the wearing plates. The fastening screws extend through the webs and are screwed into the wearing plates. If the wearing plates are worn down, the ends of the fastening screws are also worn away. The fastening screws thus are, unable to hold any longer and gradually fall out of the bore in the webs under the influence of the vibrations of the track-type undercarriage. This can be recognized immediately during the normal daily inspection, and new wearing plates can be mounted with new fastening screws to correct the problem.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.